Intent
A multiplayer session’s state — who’s in, what roles, what mode, what map — must stay accurate throughout the session’s lifecycle. If state gets desynced or corrupted, joining players see wrong information and existing players are dropped into wrong contexts. XR-067 requires titles maintain session state through every reasonable perturbation.Applies to
Every title with multiplayer session state (MPSD or modern equivalent).Requirement
Your title MUST:- Keep the MPSD session state in sync with the runtime session on every state transition (member join, member leave, role change, mode change, host migration).
- Handle host migration correctly when the host disconnects — elect a new host, transfer authoritative state, notify remaining members.
- Handle member disconnect — remove the departed member from session state, notify remaining members, adjust joinability if the session is now not full.
- Handle network glitches — transient network loss on the host must not tear down the session if recovery is quick.
- Handle platform events — sign-out, Quick Resume, controller change — without corrupting the session for other members.
- Persist session identity correctly through host migration so join-from-presence still finds the migrated session.
- Clean up sessions when they naturally end (all members leave, game completes) so the session doesn’t ghost in MPSD.
- Show session state inconsistently across members.
- Allow a stale MPSD session to persist after the runtime session has ended.
- Drop all remaining members when the host disconnects.
- Fabricate members in the session state that aren’t actually connected.
Tested scenarios
- Host a 4-player session. Have the host disconnect (network pull). Verify host migration; verify remaining 3 members continue.
- Have a non-host member disconnect. Verify graceful removal from state.
- Rapidly join / leave the session. Verify session state stays consistent.
- Change game mode mid-lobby. Verify state propagates to all members.
- Sign out mid-session. Verify session state updates for the remaining members.
Best practices
- Design an authoritative host or arbitrated session so there’s a single source of truth on session state.
- Use MPSD writes carefully — rate-limit them to avoid throttling under XR-132.
- Reconcile after network glitches — on reconnect, re-read MPSD state and diff against runtime.
- Timebound host-migration — if no new host is elected in a bounded time, tear down cleanly rather than hanging.
Related XRs
- XR-064 — Joinable sessions.
- XR-070 — Friends list.
- XR-074 — Loss of connectivity.
- XR-115 — Adding / removing users during gameplay.
- XR-124 — Game invitations.
- XR-132 — Service access limits.